This invention relates to a shift mechanism in a manual transmission of such a type that when a reverse idler gear mounted on a reverse idler shaft is shifted by a reverse shifting operation, a clutch hub sleeve of a synchromesh unit for a forward speed gear, which unit is mounted on a counter shaft and is adapted to rotate with the counter shaft, is moved in a reverse direction relative to the forward speed geared position.
A reverse shift mechanism in a manual transmission is generally of a sliding mesh type or a constant mesh type except for some kinds of automobile. Namely, as a reverse shifting operation is carried out under a rest condition of the automobile, a synchromesh mechanism as is used for a forward shift mechanism is not employed for a reverse shift mechanism. However, in the case that the number of revolution of a counter shaft, which revolution is transmitted from an input shaft after releasing a clutch, is large, the number of revolution of meshed gears by a reverse shift operation is relatively large and as a result, a gear buzzing and a body shock sometimes arise to render a driver uncomfortable or to rarely damage gears, which is notable for a sliding mesh type.
The number of revolution of a counter shaft system after releasing a clutch recently tends to become large. This is caused by such reasons that a revolution transmitting efficiency of a transmission at lower temperatures has been improved and a lubricating oil having a low viscosity has been widely employed for the aim of smoother sliding operation, and further an engine idling speed is set to a higher value because of generalization of air conditioner mounting automobiles.